The concept of injecting water into the combustion space of an internal combustion engine to form steam which can be used as a working fluid in cooperation with the gaseous products of combustion has been long known and used in the prior art. In general, the concept has involved injecting the water into the combustion space when the piston has already started to move through its power or expansion stroke and at a time when the piston is relatively hot, so as to immediately convert the water into steam. The contact of the water with the piston head also assists in cooling the piston, which is important, particularly with pistons of large diameter. In addition, the insertion of water into the cylinder to form steam, at the proper time, promotes more complete combustion of the fuel, thereby avoiding or limiting the formation of carbon. Also, the presence of the steam in the cylinder has been found to improve quietness of operation and fuel economy.
In the previously employed engines of this type, it has been found that in order to prevent or minimize interference with fuel combustion, the timing of the water injection is quite critical, and there is a necessity for accurately controlling the point at which the water is injected after the beginning of the power or expansion stroke of the associated piston. In the previously used systems, accurately machined cams, rocker arm assemblies, and other complex mechanisms have been employed to time and suitably delay the water injection. These devices are quite expensive, are subject to malfunction due to wear or vibration, and require a high degree of careful maintenance. Due to the extra moving parts involved, the associated engines are quite noisy, and extra lubrication is required to insure smooth operation. Therefore, improvement and simplification of the water injection timing means would be definitely advantageous in this art.
The present state of the art appears to be well illustrated by the following prior U.S. Pat. Nos., found as a result of a preliminary search:
Weiss, 704,995;
Rogers, 1,197,546;
Dempsey, 1,261,779;
Carlson, 1,727,860;
Kroll, 3,990,408;
Sanda et al, 4,063,536.